Effects of Dredge Material Placement on Macroinvertebrate Communities: Phase 1

ID: 8809; issued October 1, 1998INHS Technical Report prepared for Rock Island District, US Army Corps of Engineer

Trends in Characteristics of Yellowstone Lake Cutthroat Trout, Associated Factors, and Evidence of a Population Shift

Comprehensive time-series data for Yellowstone cutthroat trout (Oncorhynchus clarkia bouvieri; YCT) based on samples taken between 1977 and 2007 from the spawning run (spring; n = 29 yrs) of a tributary (Clear Creek) of Yellowstone Lake or caught in gill nets set (fall; n = 30 years) at established locations in the lake were examined to identify (1) associations between population characteristics within and between capture methods, as well as temporal trends in those characteristics, (2) evidence of informative shifts in population characteristics, and (3) factors that may have importantly affected the dynamics of the lacustrine-adfluvial YCT population of the tributary. Temporal increases in mean TL of YCT in the spawning run and of prespawners, i.e., YCT whose gonads indicated the fish would have spawned the next year, in the gillnet catch and concurrent declines in run size and prespawner catch were suggestive of an effect of YCT population density on the somatic growth of the fish. Similarly, a concurrent increase in mean TL of gillnetted YCT 100-199 mm long was indicated by the polynomial regression results, which also suggested statistical change points in the temporal trends for each of those variables. Contrasting those trends was that for mean TL of gillnetted YCT 200-299 mm long, whose general decline during the past two decades was attributed to predation by nonnative lake trout (Salvelinus namaycush). Collectively, these trends provided evidence of a YCT population shift. Correlation results indicated YCT in the spawning run could not be unequivocally assigned to any particular lake region. Multiple regression analyses showed that Clear Creek run size was strongly affected by parental run size 5 yrs earlier and a measure of climate 5 yrs earlier

Is Habitat Type a Useful Predictor of the Outcome of Interactions between Tubifex tubifex and Myxobolus cerebralis, the Causative Agent of Salmonid Whirling Disease?

The aquatic oligochaete Tubifex tubifex is the intermediate host for the parasite, Myxobolus cerebralis, which causes salmonid whirling disease (WD). Although the relationship between WD severity in salmonids and infection in T. tubifex is not well understood, previous research suggests that variation within local stream populations of T. tubifex may be an important determinant of parasite success. Our goals were to examine relationships among habitat features, abundance, infection prevalence, genetic diversity and susceptibility of T. tubifex, and WD risk in Yellowstone cutthroat trout spawning tributaries in Yellowstone National Park, where M. cerebralis was detected in 1998. Abundance of tubificids and T. tubifex, and infection prevalence in T. tubifex were higher in unconfined habitat types than in confined habitat types. Tubifex tubifex belonging to mtDNA lineages III, which are considered moderately susceptible to M. cerebralis, were also more abundant in unconfined habitats than confined habitats. We assessed the susceptibility of four genetically distinct strains of lineage III T. tubifex to M. cerebralis in the laboratory. Strains were established from field collected T. tubifex. All strains were susceptible to infection by M. cerebralis and strains from unconfined habitats amplified the parasite only slightly more than strains from confined habitats. These results suggest habitat type may influence variability in WD risk by affecting the outcome of interactions between T. tubifex and M. cerebralis in the field

Effects of Fish Restoration Practices on Amphibians in Yellowstone National Park, Wyoming

Throughout the Western United States, fisheries managers are attempting to restore native cutthroat trout (Onchorynchus clarkii) populations by removing nonnative fish species. A new formulation of the EPA approved piscicide rotenone (CFT Legumine) is increasingly being used as a method to accomplish this removal. Because fish restoration projects bring about an abrupt change to aquatic environments, it is important to consider their immediate and long-term effects on non-target species, such as amphibians. We assessed the effects of fish removal on amphibians in Yellowstone National Park (YNP) by investigating the toxicity of rotenone to and the long-term impacts of removing fish on local amphibian populations. CFT Legumine (5% rotenone) was applied to High Lake in YNP (2006) to remove stocked Yellowstone cutthroat trout (O. c. bouvieri). To determine toxicity, amphibian surveys were conducted immediately prior to the treatment to obtain pre-treatment tadpole population estimates. Post-treatment surveys were conducted both immediately, for assessing treatment-related mortality (during and after application), and 1, 2, and 3 years following to obtain tadpole abundance estimates in the years after application and to address the long-term effects of fish removal and reintroduction. The results of the toxicity trials revealed that in the 24 hrs following application, rotenone was lethal to gill-breathing amphibian tadpoles and nonlethal to non-gill breathing metamorphs, juveniles, and adults. In the years following, tadpole repopulation occurred at levels above the pre-treatment abundance estimate, though both tadpole abundance and distribution appeared correlated with fish presence

An Evaluation of Lake Trout Suppression in Yellowstone Lake, Yellowstone National Park

Introduced lake trout (Salvelinus namaycush) threaten to extirpate native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) from Yellowstone Lake, Yellowstone National Park. A National Park Service gill netting program has removed nearly 400,000 lake trout from Yellowstone Lake since 1995. Lake trout population size has not been estimated; therefore, it is difficult to determine the proportion that has been removed. Our objectives were to (1) examine catch as a function of effort to determine if the suppression program has caused lake trout abundance to decline, (2) determine if certain population metrics have changed over time as a function of harvest, and (3) develop age-structured models to determine the level of mortality required to cause population growth rate to decline below 1.0 (replacement). Catch has continued to increase as a function of effort, indicating lake trout abundance is increasing. Population metrics were not clearly indicative of a response to harvest, but were comparable to North American lake trout populations where harvest has occurred. Results from an age-structured matrix model determined the rate of population growth was 1.1 given the current rate of fishing mortality and that population growth rate would be 1.3 in the absence of fishing mortality. The current rate of population growth is positive; however, it is slower than it would be in the absence of lake trout suppression. Fishing mortality needs to increase by at least 10 percent to reduce population growth rate below 1.0 in the future

The Long-term Illinois River Fish Population Monitoring Program F-101-R (Final Report)

Segments 6-10 issued November 1999Report issued on: November 1999INHS Technical Report prepared for Illinois Department of Natural Resources and US Fish and Wildlife Servic

Effects of Dredge Material Placement on Macroinvertebrate Communities

ID: 8857; issued November 1, 1999INHS Technical Report prepared for US Army Corps of Engineer

The Long-Term Illinois River Fish Population Monitoring Program, Project F-101-R-11 Annual Report

Report issued on: June 2000Project F-101-R-11 Annual Report issued June 1, 2000INHS Technical Report prepared for Illinois Department of Natural Resource

The Long-Term Illinois River Fish Population Monitoring Program F-101-R-9 Annual Report

Report issued on: May 1998F-101-R-9 Annual Report issued May 1998INHS Technical Report prepared for Illinois Department of Natural Resource

The Long-Term Illinois River Fish Population Monitoring Program F-101-R-8 Annual Report

F-101-R-8 Annual Report issued December 1, 1997Report issued on: December 1997INHS Technical Report prepared for Illinois Department of Natural Resource